You’re going to be looking at the
Innate Immune Response in this lecture.
In another lecture, you’ll look
at the Adaptive Immune Response.
It’s very important to appreciate
that these two types of immune
response, the innate and the adaptive actually work together.
They’re fully integrated types of responses,
not two entirely separate responses.
However, there are two features that
distinguish innate and adaptive response.
Firstly, innate responses
are broadly specific.
They don’t recognize single antigens in a very highly
specific way, which is a feature of the adaptive response.
And secondly, innate immune
responses are the same, however many
times the infection is encountered,
they react to the same extent.
This is in contrast to the adaptive response which shows
a property called immunological memory where upon a
second encounter, with the same pathogen, a much faster
and stronger secondary immune response is elicited.
So we’re going to focus on the innate immune response
but remember that this doesn’t act in isolation.
It acts together with
the adaptive response.
Let us look at the events occurring
during the innate response.
Initially there needs to
be recognition of a threat.
The immune system needs to know that there’s an infection
or a toxin or tissue damage that it needs to respond to.
There needs to be activation of innate immune cells and of some
molecules that collectively are called the complement system.
There also needs to be the production of other molecules called
cytokines, chemokines, acute phase proteins and defensins.
Also, upregulation of cell adhesion
molecules is required, as is
the recruitment of cells to the
site of infection or tissue damage.
Having detected a threat and beginning to make a response,
then obviously, there needs to be elimination of the threat.
In other words, elimination of
the stimulus to the response.
Following elimination of the threat, there
needs to be resolution of the response
and tissue repair of any damage that has
occurred as part of the immune response.